Search PubMed⌕ Search

Biomedical subjects

R G Dluhy

Publications and source records attributed to R G Dluhy.

At least 109 records · Page 6Linked to original sources
PubMed1972

Glucagon-initiated human growth hormone release: a comparative study.

Human growth hormone (HGH) responses in 20 healthy adults to subcutaneous glucagon, arginine infusion and tolbutamide and insulin hypoglycemia were compared. HGH rose in all four tests. HGH response to glucagon was also studied in 49 patients with suspected pituitary insufficiency, of whom 25 also later received an arginine infusion; an abnormal response to glucagon was the most frequent functional abnormality and often HGH was the only anterior pituitary hormone of which a deficiency was detectable. In seven subjects (two healthy controls and five patients with suspected hypopituitarism) there was a subnormal HGH response to arginine but a normal response to glucagon. It is concluded that glucagon is a simple and effective stimulus to HGH release, equal or superior to arginine, tolbutamide and insulin, and is an important test of anterior pituitary function.

17-Hydroxycorticosteroids↗
PubMed1972

Studies of the control of plasma aldosterone concentration in normal man. I. Response to posture, acute and chronic volume depletion, and sodium loading.

The peripheral plasma levels of aldosterone, renin activity (PRA), potassium, corticosterone, cortisol, and in some cases angiotensin II, were measured in normal subjects undergoing postural changes, acute diuretic-induced volume depletion, and alterations in dietary sodium. On a 10 mEq sodium/100 mEq potassium intake, subjects supine for 3 consecutive days had identical diurnal patterns of PRA, angiotensin II, aldosterone, cortisol, and corticosterone, with peaks at 8 a.m. and nadirs at 11 p.m. With an increase in sodium intake to 200 mEq, plasma levels of aldosterone and PRA fell to one-third their previous levels but the diurnal pattern in supine subjects was unchanged and again parallel to that of cortisol and corticosterone. There was no diurnal variation of plasma potassium on either sodium intake in the supine subjects. On a 10 mEq sodium/100 mEq potassium intake, supine 8 a.m. plasma aldosterone (55+/-7 ng/100 ml) and PRA (886+/-121 ng/100 ml per 3 hr) increased by 150-200% after subjects were upright for 3 hr. However, even though the patients maintained an upright activity pattern, there was a significant fall in plasma aldosterone to 33+/-5 ng/100 ml at 11 p.m. Potassium levels varied in a fashion parallel to aldosterone and PRA. Plasma cortisol and corticosterone had a diurnal pattern similar to that found in supine subjects. In response to acute diuretic-induced volume depletion, the nocturnal fall in aldosterone levels did not occur. The 11 p.m. value (102+/-20 ng/100 ml) and the 8 a.m. value postdiuresis (86+/-15 ng/100 ml) were both significantly greater than the prediuresis levels. PRA showed a similar altered pattern while potassium levels fell throughout the day. In some but not all studies, changes in plasma aldosterone coincided with changes in plasma cortisol, corticosterone, and/or potassium. However, in all studies, changes in plasma aldosterone were invariably associated with parallel changes in plasma renin activity and/or angiotensin II levels. These findings support the concept that PRA is the dominant factor in the control of aldosterone when volume and/or dietary sodium is altered in normal man.

Adult↗
PubMed1972

Studies of the control of plasma aldosterone concentration in normal man. II. Effect of dietary potassium and acute potassium infusion.

The responses of plasma aldosterone, cortisol, and corticosterone to an infusion of 75 mEq of potassium chloride over 120 min were studied in 10 normal subjects. Five subjects were fed a 10 mEq and five a 200 mEq sodium diet, while all subjects ingested 40 mEq and 200 mEq potassium sequentially. Two potassium infusions were performed in each subject when in balance on a fixed sodium intake and low and then high potassium diets. Regardless of dietary intake, increases of serum potassium of 0.5-1.5 mEq/liter above preinfusion levels were usually associated with significant increments in plasma aldosterone concentration. Our data agree with previous evidence that the potassium ion stimulates the adrenal cortex directly to secrete aldosterone. Peripheral renin activity did not increase after the potassium infusion. Plasma cortisol and corticosterone levels generally followed the expected diurnal decline during the infusion, implying that ACTH secretion did not increase. The plasma aldosterone response to incremental changes in serum potassium was linear on each of the four diets. The slopes of these linear relationships increased significantly when the potassium intake was increased from 40 to 200 mEq. No increase in slope occurred on either potassium intake when dietary sodium was restricted from 200 to 10 mEq. Thus, identical increases in serum potassium were associated with greater increments in plasma aldosterone above preinfusion levels on either sodium intake when the 200 mEq potassium diet was compared with the 40 mEq potassium intake.

Adrenal Glands↗
PubMed1972

Studies of the control of plasma aldosterone concentration in normal man. 3. Response to sodium chloride infusion.

The peripheral plasma levels of aldosterone, renin activity, potassium, sodium, corticosterone, and cortisol were measured in six normal subjects four times daily-10 a.m., 2 p.m., 5 p.m., 11 p.m.-on 3 consecutive days. A constant daytime activity program was maintained throughout the study. After 5 days on a 10 mEq sodium/100 mEq potassium isocaloric intake, the mean upright 10 a.m. plasma renin activity was 1773+/-186 ng/100 ml per 3 hr and the mean plasma aldosterone, 81+/-14 ng/100 ml. These two parameters fell continuously throughout the day parallel to the fall in plasma cortisol and corticosterone. In response to 2 liters of normal saline infused from 10 a.m. to 2 p.m. on 2 consecutive days, plasma aldosterone levels fell significantly to 13+/-5 ng/100 ml at 2 p.m. after the 1st day's infusion and to 6+/-1 ng/100 ml at 2 p.m. after the 2nd. Plasma renin activity demonstrated a parallel fall to 368+/-63 ng/100 ml per 3 hr and 189+/-27 ng/100 ml per 3 hr at 2 p.m. on the 1st and 2nd days, respectively. There was no significant alteration in plasma levels of cortisol, corticosterone, potassium, or sodium on the 2 days of sodium loading in comparison with the control day. In an additional study, five normal supine subjects received 500 ml saline/hr for 6 hr. As in the 2 day study, plasma aldosterone and renin activity had parallel decrements at 1, 2, 4, and 6 hr after the start of the saline infusion. From these studies, it is concluded that plasma renin activity is the dominant factor controlling plasma aldosterone when sodium-depleted normal subjects are acutely repleted.

Adult↗